MODEL CLAMP AND ITS APPLICATION TO SYNCHRONIZATION OF RABBIT SINOATRIAL NODE CELLS

A method for coupling an isolated cardiac cell to a simulated cardiac cell, i.e., the real-time solution of a mathematical model, of such ce ll, has been developed. With this ''model clamp'' technique, the real cell and the model cell are coupled by any desired value of intercellu lar coupling conductance, producing the effect of mutual interaction b y electrical coupling through gap junctional channels. We implemented the model clamp technique with our previously published model of an is olated rabbit sinoatrial node cell. We used this model clamp system to study synchronization of sinoatrial node cells with regard to the cri tical value of intercellular coupling conductance required for frequen cy entrainment and tile common interbeat interval during frequency ent rainment. This common interbeat interval lay between the intrinsic int ervals of the real cell and the model cell, but was closer to that of the intrinsically faster beating cell. Critical coupling conductance i ncreased with increasing difference in intrinsic interbeat interval of the real cell and the model cell and ranged between 50 and 300 pS in 11 hybrid cell pairs.